40
6B
Domestic water piping
Installation & Service Manual
Scalding
This combi heater can deliver scalding temperature water
at any faucet in the system. Be careful whenever using hot
water to avoid scalding injury. Certain appliances such as
dishwashers and automatic clothes washers may require
increased temperature water. By setting the thermostat
on this combi heater to obtain the increased temperature
water required by these appliances, you may create the
potential for scald injury. To protect against injury, you
MUST install an ASSE 1070 anti-scald mixing valve in the
water system. This valve will reduce point of discharge
temperature by mixing cold and hot water in branch
supply lines. Such valves are available from the local
plumbing supplier.
The following table (Table 6B) details the relationship of
water temperature and time with regard to scald injury
and may be used as a guide in determining the safest water
temperature for your applications.
APPROXIMATE TIME / TEMPERATURE
RELATIONSHIPS IN SCALDS
120°F
More than 5 minutes
125°F
1 1/2 to 2 minutes
130°F
About 30 seconds
135°F
About 10 seconds
140°F
Less than 5 seconds
145°F
Less than 3 seconds
150°F
About 1 1/2 seconds
155°F
About 1 second
Table 6B Approximate Time / Temperature Scald Chart
Water chemistry
Any damage or failure resulting from improper water
chemistry, or heating anything other than potable water.
DEFINITION OF POTABLE WATER - Potable water
is defined as drinkable water supplied from utility or
well water in compliance with EPA secondary maximum
contaminant levels (40 CFR Part 143.3) as shown in Table
6C - Potable Water.
Potable Water Levels
Contaminant
Level
Aluminum
0.05 to 0.2 mg/l
Chloride
250 mg/l
Color
15 color units
Copper
1.0 mg/l
Corrosivity
Non-corrosive
Fluoride
2.0 mg/l
Foaming Agents
0.5 mg/l
Iron
0.3 mg/l
Manganese
0.05 mg/l
Odor
3 threshold odor number
pH
6.5 - 8.5
Silver
0.1 mg/l
Sulfate
250 mg/l
Total Dissolved Solids (TDS)
500 mg/l
Zinc
5 mg/l
Table 6C Potable Water
Near heater piping components
1. Recirculation pump (optional):
Field supplied. The recirculation pump shuts off flow
at the desired DHW set point.
2. Check
valves:
Field supplied. Check valves are recommended for
installation as shown in FIG.’s 6-7 through 6-9. Failure
to install check valves could result in a reverse flow
condition during pump(s) off cycle.
3. Domestic hot water isolation valves:
Field supplied. Full port ball valves are
required. Failure to use full port ball valves could
result in a restricted flow rate through the boiler.
4. Anti-scald mixing valve:
Field supplied. For use when utilizing the DHW option.
An ASSE 1070 anti-scald mixing valve is required.
5. Unions:
Field supplied. Recommended for unit serviceability.
6. Temperature and pressure gauge:
Field supplied. It is the responsibility of the contractor
to provide and install the temperature and pressure
gauge on the boiler water outlet.
7. Pressure
relief
valve:
Field supplied. The pressure relief valve is sized to
ASME
specifications.
F I R E T U B E C O M B I
™
WARNING
An ASSE 1070 anti-scald mixing
valve is REQUIRED. Failure to
comply could result in property
damage, severe injury, or death.
